Path constraints problem
Basically the constrained object (a mesh, a bone, an empty) has to be set (or keyframed) in the world origin location (0,0,0) when the follow path constraint is set up, so that in the first frame of the constrained action it will be exactly where the first point of the path is, and in the last on the last.
If you still have offset problems and you don't want to change your elements you can create  an empty, set it as path constrained, and parent the root bone of your armature to the empty, then move the root bone to the appropriate location on the first frame.